Visual stimulus structure, visual system neural activity, and visual behavior in young human infants.

In visual perception and information processing, a cascade of associations is hypothesized to flow from the structure of the visual stimulus to neural activity along the retinogeniculostriate visual system to behavior and action. Do visual perception and information processing adhere to this cascade near the beginning of life? To date, this three-stage hypothetical cascade has not been comprehensively tested in infants. In two related experiments, we attempted to expose this cascade in 6-month-old infants. Specifically, we presented infants with two levels of visual stimulus intensity, we measured electrical activity at the infant cortex, and we assessed infants' preferential looking behavior. Chromatic saturation provided a convenient stimulus dimension to test the cascade because greater saturation is known to excite increased activity in the primate visual system and is generally hypothesized to stimulate visual preference. Experiment 1 revealed that infants prefer (look longer) at the more saturated of two colors otherwise matched in hue and brightness. Experiment 2 showed increased aggregate neural cortical excitation in infants (and adults) to the more saturated of the same pair of colors. Thus, experiments 1 and 2 taken together confirm a cascade: Visual stimulation of relatively greater intensity evokes relatively greater levels of bioelectrical cortical activity which in turn is associated with relatively greater visual attention. As this cascade obtains near the beginning of life, it helps to account for early visual preferences and visual information processing.

How the Environmental influences on Child Health Outcome (ECHO) Cohort can spur discoveries in environmental epidemiology.

NIH's Environmental influences on Child Health Outcome (ECHO) program is an innovative, large, collaborative research initiative whose mission is to enhance the health of children for generations to come. The goal of the ECHO Cohort is to examine effects of a broad array of early environmental exposures on child health and development. It includes longitudinal data and biospecimens from over 100,000 children and family members from diverse settings across the U.S. ECHO investigators have published collaborative analyses showing associations of environmental exposures--primarily in the developmentally sensitive pre-, peri-, and post-natal periods--with preterm birth and childhood asthma, obesity, neurodevelopment, and positive health. Investigators have addressed health disparities, joint effects of environmental and social determinants, and effects of mixtures of chemicals. The ECHO Cohort is now entering its second 7-year cycle (2023-2030), which will add the preconception period to its current focus on prenatal through adolescence. Through a controlled access public use database, ECHO makes its deidentified data available to the general scientific community. ECHO Cohort data provide opportunities to fill major knowledge gaps in in environmental epidemiology, and to inform policies, practices, and programs to enhance child health.

Electrophysiological Evidence for Interhemispheric Connectivity and Communication in Young Human Infants.

Little is known empirically about connectivity and communication between the two hemispheres of the brain in the first year of life, and what theoretical opinion exists appears to be at variance with the meager extant anatomical evidence. To shed initial light on the question of interhemispheric connectivity and communication, this study investigated brain correlates of interhemispheric transmission of information in young human infants. We analyzed EEG data from 12 4-month-olds undergoing a face-related oddball ERP protocol. The activity in the contralateral hemisphere differed between odd-same and odd-difference trials, with the odd-different response being weaker than the response during odd-same trials. The infants' contralateral hemisphere "recognized" the odd familiar stimulus and "discriminated" the odd-different one. These findings demonstrate connectivity and communication between the two hemispheres of the brain in the first year of life and lead to a better understanding of the functional integrity of the developing human infant brain.

Development of object control in the first year: emerging category discrimination and generalization in infants' adaptive selection of action.

This research examined the development of adaptive generalization in infants' object-directed actions. Infants ages 9 and 12 months participated in an object manipulation task with stimulus objects from 2 categories that differed in shape and weight and that bore a consistent shape or weight correspondence. Weight differences between categories affected infants' actions required to handle objects effectively. Infants manually explored objects from both categories and then were tested for their selection of different actions between categories and their generalization to novel exemplars within categories. Nine-month-olds provided no evidence of category differentiation and generalization; however, 12-month-olds adapted their actions selectively for objects of each category and generalized those actions to novel objects within categories. A second sample of 9-month-olds who were examined in a simplified task with just one object per weight level successfully adapted their actions by weight. Together, the findings provide evidence for the development of selection and generalization in manipulative action across the second half of the first year of life.

Differentiated brain activity in response to faces of "own" versus "unfamiliar" babies in primipara mothers: an electrophysiological study.

Experiences with one's own infant attune the parent nervous system to infant stimuli. To explore the effects of motherhood on brain activity patterns, electroencephalogram (EEG) was recorded while primipara mothers of 3- and 6-month-olds viewed images of faces of their own child and an unfamiliar but appearance-matched child. Mothers of 3- and 6-month-olds showed equivalent early-wave (N/P1 "visual" and N170 "face-sensitive") responses to own and unfamiliar baby faces but differentiating late-wave (N/P600 "familiar/ novel") activity to own versus unfamiliar infant faces. Based on 3 months experience with their own infant's face, mothers' brain patterns give evidence of distinctive late-wave (recognition) sensitivity.

Brain dynamics in young infants' recognition of faces: EEG oscillatory activity in response to mother and stranger.

The brain electrical responses of 3-month-old infants were compared between images of familiar and unfamiliar faces. Infants were shown images of their mothers and of appearance-matched female strangers for 500 ms per trial while their electroencephalography was recorded. Electroencephalographic signals were segmented from stimulus onset through 1200 ms, and segments were analyzed in the time-frequency domain with a continuous wavelet transform. Differentiated responses were apparent in three time windows: 370-480, 610-690, and 830-960 ms. Across response windows, event-related synchronization or desynchronization was observed in beta or gamma frequency bands at the left frontal, midline central, bilateral temporal, and right parietal sites. In conclusion, these findings provide the first evidence of organized brain activity underlying familiar face recognition in very young infants and are discussed in relation to comparable patterns that have been observed in adults.

5-Month-Olds' Categorization of Novel Objects: Task and Measure Dependence.

To examine key parameters of the initial conditions in early category learning, two studies compared 5-month-olds' object categorization between tasks involving previously unseen novel objects, and between measures within tasks. Infants in Experiment 1 participated in a visual familiarization / novelty preference (VFNP) task with 2D stimulus images. Infants provided no evidence of categorization by either their looking or their examining even though infants in previous research systematically categorized the same objects by examining when they handled them in 3D. Infants in Experiment 2 participated in a VFNP task with 3D stimulus objects that allowed visual examination of objects' 3D instantiation while denying manual contact with the objects. Under these conditions, infants demonstrated categorization by examining but not by looking. Focused examination appears to be a key component of young infants' ability to form category representations of novel objects, and 3D instantiation appears to better engage such examining.

Object perception in 5-month-old infants of clinically depressed and nondepressed mothers.

Five-month-old infants of clinically depressed and nondepressed mothers were familiarized to a wholly novel object and afterward tested for their discrimination of the same object presented in the familiar and in a novel perspective. Infants in both groups were adequately familiarized, but infants of clinically depressed mothers failed to discriminate between novel and familiar views of the object, whereas infants of nondepressed mothers successfully discriminated. The difference in discrimination between infants of depressed and nondepressed mothers is discussed in light of infants' differential object processing and maternal sociodemographics, mind-mindedness, depression, stress, and interaction styles that may moderate opportunities for infants to learn about their world or influence the development of their perceptuocognitive capacities.

Young infants' eye movements over "natural" scenes and "experimental" scenes.

Eye movements of 30 4-month-olds were tracked as infants viewed animals and vehicles in "natural" scenes and, for comparison, in homogeneous "experimental" scenes. Infants showed equivalent looking time preferences for natural and experimental scenes overall, but fixated natural scenes and objects in natural scenes more than experimental scenes and objects in experimental scenes and shifted fixations between objects and contexts more in natural than in experimental scenes. The findings show how infants treat objects and contexts in natural scenes and suggest that they treat more commonly used experimental scenes differently.

Perception of object-context relations: eye-movement analyses in infants and adults.

Twenty-eight 4-month-olds' and twenty-two 20-year-olds' attention to object-context relations was investigated using a common eye-movement paradigm. Infants and adults scanned both objects and contexts. Infants showed equivalent preferences for animals and vehicles and for congruent and incongruent object-context relations overall, more fixations of objects in congruent object-context relations, more fixations of contexts in incongruent object-context relations, more fixations of objects than contexts in vehicle scenes, and more fixation shifts in incongruent than congruent vehicle scenes. Adults showed more fixations of congruent than incongruent scenes, vehicles than animals, and objects than contexts; equal fixations of animals and their contexts but more fixations of vehicles than their contexts; and more shifts of fixation when inspecting animals in context than vehicles in context. These findings for location, number, and order of eye movements indicate that object-context relations play a dynamic role in the development and allocation of attention.

Discrimination of facial expression by 5-month-old infants of nondepressed and clinically depressed mothers.

Five-month-old infants of nondepressed and clinically depressed mothers were habituated to either a face with a neutral expression or the same face with a smile. Infants of nondepressed mothers subsequently discriminated between neutral and smiling facial expressions, whereas infants of clinically depressed mothers failed to make the same discrimination.

Experience-based and on-line categorization of objects in early infancy.

What processes do infants employ in categorizing? Infants might categorize on line as they encounter category-related entities; alternatively, infants might depend on prior experience with entities in formulating categories. These alternatives were tested in forty-four 5-month-olds. Infants who were familiarized in the laboratory with a category of never-before-seen objects subsequently treated novel objects of the same category as familiar-they categorized on line-just as did infants who were exposed to objects from the same category at home for 2 months leading to their laboratory assessment of object categorization. Infants with home experience also recognized novel category objects as familiar from the outset-that is, prior experience with category exemplars was brought to bear in laboratory tasks.

Infant object categorization transcends diverse object-context relations.

Infants' categorization of objects in different object-context relations was investigated. The experiment used a multiple-exemplar habituation-categorization procedure where 92 6-month olds formed categories of animals and vehicles embedded in congruent, incongruent, and homogeneous object-context relations. Across diverse object-context relations, infants habituated to multiple exemplars within a category and categorized novel members of both animal and vehicle categories. Infants showed a slight advantage for categorizing animals. Infant object categorization appears to be robust to diversity in object-context relations.

Mechanisms of Visual Object Recognition in Infancy: Five-Month-Olds Generalize Beyond the Interpolation of Familiar Views.

This work examined predictions of the interpolation of familiar views (IFV) account of object recognition performance in 5-month-olds. Infants were familiarized to an object either from a single viewpoint or from multiple viewpoints varying in rotation around a single axis. Object recognition was then tested in both conditions with the same object rotated around a novel axis. Infants in the multiple-views condition recognized the object, whereas infants in the single-view condition provided no evidence for recognition. Under the same 2 familiarization conditions, infants in a 2nd experiment treated as novel an object that differed in only 1 component from the familiar object. Infants' object recognition is enhanced by experience with multiple views, even when that experience is around an orthogonal axis of rotation, and infants are sensitive to even subtle shape differences between components of similar objects. In general, infants' performance does not accord with the predictions of the IFV model of object recognition. These findings motivate the extension of future research and theory beyond the limits of strictly interpolative mechanisms.

Multidimensional shape similarity in the development of visual object classification.

The current work examined age differences in the classification of novel object images that vary in continuous dimensions of structural shape. The structural dimensions employed are two that share a privileged status in the visual analysis and representation of objects: the shape of discrete prominent parts and the attachment positions of those parts. Experiment 1 involved a triad classification task in which participants at each of three different ages (5 years, 8 years, and adult) classified object images from two distinct stimulus sets. Across both sets, the youngest children demonstrated a systematic bias toward the shape of discrete parts during their judgments. With increasing age, participants increasingly came to select both the shape and the position of parts when classifying the images. The findings from Experiment 2 indicate that the local shape bias observed in young children's classifications is not merely a consequence of a discrimination advantage for that dimension. Results are discussed in relation to corresponding age-related changes in other functional contexts of visual processing.

What do two-year-olds understand about hidden-object events?

Preferential-looking studies suggest that by 2 months of age, infants may have knowledge about some object properties, such as solidity. Manual search studies of toddlers examining these same concepts, however, have failed to provide evidence for the same understanding. Investigators have recently attempted to reconcile this disparity but failed to control for the visual novelty of test outcomes. The current design corrected this problem and also tested toddlers' predictions of the object's location. The task involved the same events and apparatus that have been used in manual search tasks but used looking as the dependent measure. Children looked longer when an agent opened the correct door and found no ball than when an incorrect door was opened to reveal no ball. A 2nd experiment indicated that children's preferential-looking performance did not differ from that in manual search tasks simply because additional response time had been allowed to respond. Previous comparisons of looking versus reaching tested children's postdiction response to an object in an unexpected location, but these findings indicate that toddlers can predict where the object should be.

Intraobserver reliability of the Teller Acuity Card procedure in infants with perinatal complications.

PURPOSE: Intraobserver test-retest reliability of the Teller Acuity Card (TAC) procedure for estimating grating acuity was assessed in 79 infants who had been treated in a neonatal intensive care unit for preterm birth and/or other perinatal complications. METHODS: Subjects were tested monocularly at one or more of four different age intervals that ranged between 2.5 and 18.5 mo corrected age. Testers were masked to the location and spatial frequency of the grating on each card. RESULTS: Of the intraobserver test-retest scores, 91% differed by no more than one octave and 68% differed by no more than 0.5 octave. Intraobserver agreement was similar to that reported previously for healthy, preterm infants. Reliability was uniform between infants of differing levels of risk for abnormal visual development but bore effects of low tester ratings of confidence. CONCLUSIONS: The results demonstrate the reliability of the TAC procedure but suggest that test sessions should be repeated when tester confidence in validity of results is low.

Facilitating children's understanding of misinterpretation: explanatory efforts and improvements in perspective taking.

The authors investigated children's understanding of how mistaken beliefs can arise through misinterpretation of ambiguous information. Children (N = 91), aged 4 to 5 years, were given pre- and posttests on their ability to infer a puppet's interpretation of a restricted-view drawing after the puppet had been led to an erroneous expectation about the drawing's identity. Before the posttest, the children received either self-explanation training or other-explanation training in which they explained the source of their own or a puppet's misinterpretations of drawings; a control group received no training. The children who received training improved from pre- to posttest, and those who had practiced explaining misinterpretations by referring to previously viewed pictures or to features of a target picture showed the greatest improvement. These results indicate that learning to explain misinterpretations can help children recognize situations in which misinterpretations are likely to occur.